1. Field of the Invention
The invention relates to a portable electrical luminaire having a supporting body and having a reflector surrounding a lamp base for indirect space illumination purposes. It also relates to an electronic control device for such a luminaire.
2. Summary of the Invention
Such a portable electrical luminaire is known as a standard lamp or uplighter (torchiere lamp). In particular in the case of an uplighter or torchiere lamp, the portable electrical luminaire has, for example, a shell-shaped reflector which can be closed towards the floor of a room and open towards the ceiling of the room. As a result, a luminous means surrounded by the reflector and inserted in a lamp base produces upwardly or downwardly directed light radiation and thus indirect illumination. A halogen lamp is mainly used as the luminous means.
Such an uplighter generally has a supporting body in the form of a standard. The lamp base surrounded by the reflector for accommodating the luminous means is held on the upper standard or support end. An electrical line connected to the lamp base is passed over or through the supporting body in the form of a standard to its lower support end, on which a stand is provided for achieving the required stability for the luminaire. The connection cable, which is passed out in the region of the lower support element or stand, has a connection plug at one end which can be inserted into a power supply outlet, which is for its part electrically connected to a power supply system, for the purpose of supplying power to the luminous means. The power supply system provides, for example, an AC voltage of 120 V at a system frequency of 60 Hz.
The luminaire can have, in particular in the region of the connection cable, a switch and/or a dimmer in order to switch the illumination on and off manually or to adjust the luminous intensity manually by means of the dimmer. The uplighter can also have one or more further lamps, in particular a reading lamp, which can then be switched on and off manually using a separate switch and/or by means of a dimmer or whose luminous intensity can be adjusted manually.
The invention is based on the object of making it possible with such a luminaire or uplighter to limit the power using very simple means. In addition, a potential risk of fire should be prevented in a simple manner, in particular for the case in which a halogen lamp having an impermissibly high power is used as the luminous means.
This object is achieved according to the invention by the features of claim 1. In this regard, an electronic control device is provided which is integrated in the luminaire. This control device is designed to automatically limit the electrical power drawn from the power supply system by the luminous means to a predetermined value.
In accordance with one advantageous variant of the electronic control device, it has first means for detecting an actual current or load current. This presently detected actual current and the present actual voltage, which corresponds, for example, to a supply voltage of 120 V, is used to determine the electrical power presently drawn by the luminaire. The electronic control device uses a comparison of the power value, derived from the actual current and from the actual voltage, with a, for example, voltage-compensated reference value to limit the actual current such that the electrical power drawn by the luminaire is less than or equal to a maximum power value, in particular less than or equal to 190 W. Voltage compensation is not required for a less precise power measurement.
In one preferred embodiment, the electronic control device comprises a measurement sensor, in particular a current sensor, for measuring a power parameter. Furthermore, the electronic control device comprises a comparator, which is supplied on the input side with the value or parameter detected by the measurement sensor and a reference value. The comparator is connected on the output side to a controllable switch or switch component, for example to a MOSFET (MOS field-effect transistor) as a power semiconductor, or to a relay. The lamps or luminous means of the luminaire are disconnected by means of the relay when the maximum power value is reached and switched on again when it is undershot.
However, the electronic control device preferably comprises a controllable electronic switch in the form of a power semiconductor which can be triggered, preferably a triac, a thyristor or a GTO thyristor (gate turn-off thyristor). In this case, a triac is in principle a parallel circuit comprising two thyristors for controlling the two half-waves of an AC voltage using a single component. A thyristor is understood to mean a controllable rectifier in the form of a semiconductor. A GTO thyristor, in a corresponding manner to a conventional thyristor, can be switched on with a positive voltage pulse at the control input. In contrast to a conventional thyrsitor, the GTO thyristor can, however, also be switched off by means of a negative voltage pulse. This additional disconnection option simplifies the driving electronics in the case of a GTO thyristor.
In one expedient development, the electronic control device has an electronic amplifier having an amplifier input connected to the measurement sensor and having an amplifier output connected to the first comparator input. In addition, the controllable electronic switch, i.e. the triac, thyristor or GTO thyristor, is expediently connected to a dimmer circuit for automatically adjusting the maximum electrical power supplied to the luminous means. The power is thus expediently limited by means of phase-gating or phase-chopping control. The dimmer circuit can also be operated manually in order, if necessary, to adjust the luminous intensity of the luminous means and thus the desired brightness of the luminaire.
The electronic control device can be arranged within the luminaire between the lamp base and the connection plug of the connection cable. Accordingly, the electronic control device is, if necessary, arranged in the supporting body, in the lamp base, in the connection line or in the connection plug. Within the supporting body, the electronic control device can be fitted into its stand or into the usually vertical or upright standard.
The electronic control device can also be arranged in a separate adapter. This adapter is then designed to be plugged onto the connection plug of the luminaire and to be inserted, together with said connection plug, into a conventional power supply outlet. The adapter containing the electronic control device has, for this purpose, connection pins which are suitable for the dimensions of the connection plug and correspond to the customary connection sockets of a conventional power supply outlet. The use of such an adapter having an integrated electronic control device for limiting the power of the luminaire or the uplighter is particularly suitable for retrofitting an already existing uplighter.
Exemplary embodiments of the invention will be explained in more detail below with reference to a drawing, in which:
Mutually corresponding parts are provided with the same references in all of the figures.